Precast Arch-Shaped Overfilled Structure

ABSTRACT

An arch structure for use in forming an overfilled structure includes at least one footing and at least one precast concrete bridge element forming an open bottom arch structure that is supported on the at least one footing. The arch structure has an upper portion, that may be formed by a first half-ellipse shape, and a lower portion, that may be formed by part of a second half-ellipse shape. The upper portion and lower portion meet at an elevation along the rise of the arch structure, and such elevation defines the largest span of the arch structure. The arch structure includes lower ends that come back inward toward each other, such that the span at the bottom of the arch structure is less than the largest span.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.60/896,055, entitled “Precast Arch-Shaped Overfilled Structure”, filedMar. 21, 2007, the details of which are incorporated by reference as iffully set forth herein.

TECHNICAL FIELD

The present application relates generally to open bottom precastconcrete arch structures of the type to be buried in the ground to forman overfilled structure, and more specifically to such a precast archstructure having a unique configuration that facilitates high overfilldepths.

BACKGROUND

Various configurations for precast concrete arch structure have beenused. It would be desirous to provide a configuration that is bothadapted to high overfill applications and is also cost effective.

SUMMARY

In one aspect, an overfilled structure includes a footing and first andsecond precast concrete bridge elements that have upper ends connectedby a crown joint. The precast concrete bridge elements form an openbottom arch structure that is supported on the footing. The footingextends the full span of the lower end of the arch structure andincludes spaced apart upwardly facing recesses to receive the lower endsof the precast concrete bridge elements. The precast bridge elements aresized and shaped such that the resulting arch structure has an upperportion that is formed by a first half-ellipse shape and a lower portionformed by part of a second half-ellipse shape. The two half-ellipseshapes meet at an elevation along the rise of the arch structure, andsuch elevation defines the largest span of the arch structure. Theresulting arch structure includes lower ends that come back inwardtoward each other, such that the span at the bottom of the archstructure is less than the largest span.

In another aspect, an arch system for use in forming an overfilledstructure includes at least one footing and at least one precastconcrete bridge element forming an open bottom arch structure that issupported on the at least one footing. The arch structure has an upperportion and a lower portion that meet at an elevation along the rise ofthe arch structure, and such elevation defines the largest span of thearch structure. The arch structure includes lower ends that come backinward toward each other, such that the span at the bottom of the archstructure is less than the largest span.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of an embodiment of an arch structure;

FIG. 2 is a section view of the arch structure of FIG. 1;

FIG. 3 is a detail, section view of an embodiment of a crown joint ofthe arch structure of FIG. 1;

FIG. 4 is a detail view of the crown joint of FIG. 3 with a seal;

FIG. 5 is a front view of an embodiment of a footing for use with thearch structure of FIG. 1;

FIG. 6 is a top, section view of an embodiment of a wingwall andheadwall connection for use with the arch structure of FIG. 1;

FIG. 7 illustrates an embodiment of an overfilled structure built usingthe arch structure of FIG. 1; and

FIG. 8 is a schematic elevation of an arch structure.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, an overfilled arch structure 10 includes afooting 12 that supports two precast concrete bridge elements 14 and 16.The precast concrete bridge elements 14 and 16 have respective upperends 18 and 20 that are connected by a joint 22 at the crown of the archstructure 10. Together, the two precast concrete bridge elements 14 and16 form an open bottom arch structure that is supported on the footing12 in that lower ends 24 and 26 of the precast concrete bridge elements14 and 16 opposite the upper ends 18 and 20 are spaced-apart from eachother rather than being joined like the upper ends.

The lower ends 24 and 26 are located in spaced-apart, upwardly facingrecessed portions 28 and 30 of the footing 12. The footing 12 spans thelower end of the arch structure 10 between the lower ends 24 and 26 ofthe precast concrete bridge elements 14 and 16 and includes two endportions 34 and 36 on either side of middle portion 38. The end portions34 and 36 extend upwardly to the recessed portions 28 and 30 at an angleθ relative to the horizontal. The lower ends 24 and 26 are supported atan elevation above an upper surface 40 of the middle portion 38. Thefooting 12 may be precast or cast-in-place. Earthen material around thefooting may be suitably compacted and configured to support the footing.The footing has a generally inverted polygonal approximation to an archshape (but could be a true arch shape) and serves to carry water, or itcan be filled up (with gravel etc.) and form the support of acarriageway.

Referring to FIG. 2, the precast concrete bridge elements 14 and 16 areshaped such that the resulting arch structure 10 has an upper portion 42that is formed by a half ellipse and a lower portion 44 that is formedby part of a second half ellipse. The two half ellipse shapes meet at anelevation represented by dashed line 46 along the rise of the archstructure 10, and such elevation defines the largest span S₁ of the archstructure. The resulting arch shape includes lower portions 48 and 50that curve back inward toward each other such that the span S₂ at thebottom of the arch structure 10 is less than the largest span S₁.

In some embodiments, the resulting arch structure 10 has a largest spanS₁ of between about 18 feet and 24 feet, a rise R of between about 25feet and 30 feet, a clearance C of between about 27 feet and 31 feet anda bottom span S₂ of between about 15 feet and 18 feet (e.g., a largestspan S₁ of around 21 to 22 feet, a rise R of around 26.5 to 27.5 feetand a bottom span S₂ of around 16 to 17 feet). The wall thickness T ofthe precast concrete bridge elements 14 and 16 is between about 1.1 and1.5 feet. The largest span S₁ may be at an elevation of between aboutnine and 13 feet from the lower end of the arch structure 10.

In some embodiments, a ratio of the largest span S₁ to the rise R isabout 75 to 85 percent, a ratio of the rise R to the bottom span S₂ isabout 165 to 175 percent and a ratio of the largest span S₁ to thebottom span S₂ is about 130 to 140 percent. A ratio of the height H ofthe largest span S₁ to the rise R is about 35 to 45 percent.

In a typical application the arch system may be overfilled with anysuitable material, the depth of which may vary. The overfill materialmay be compacted as necessary. In one example the overfill depth fromthe top of the arch to ground level may be between about 90 and 130 feet(e.g., between 105 and 115 feet).

Referring to FIG. 3, the joint 22 between the precast concrete bridgeelements 14 and 16 is formed by a threaded rod or bolt or bolt pair 52that extends through both of the concrete bridge elements tying themtogether at the crown of the arch structure 10. The bolt 52 extendsthrough openings 54 and 56 that are aligned to allow the bolt to passtherethrough. A sleeve 58 (e.g., formed of PVC) may be located in theopenings and about the bolt 52. Notches 60 and 62 are formed in theprecast concrete bridge elements 14 and 16 to facilitate placement ofthe bolt 52 in the openings 54 and 56. Once the bolt 52 is positioned inthe openings 54 and 56 and secured therein, grout or other fillersubstance may be used to fill the notches 60 and 62.

As can be seen by FIG. 3, upper ends 18 and 20 of the precast concretebridge elements 14 and 16 include a feature facilitating the joining andalignment of the precast concrete bridge elements. In this embodiment,the upper end 18 includes a rib 64 that is sized to fit in a groove 66of upper end 20. The bolt 52 passes through the rib 64 and the groove66. Referring to FIG. 4, the joint 22 may be sealed using a wrap 68 orother suitable sealing material.

Referring to FIG. 5, the footing 12 includes the spaced-apart, upwardlyfacing recessed portions 28 and 30 that receive the lower ends 24 and 26of the precast concrete bridge elements 14 and 16. Wedges 70 and 72(e.g., formed of hardwood) may be used to locate the lower ends 24 and26 and fill gaps within the recessed portions 28 and 30 once the lowerends are located therein. Grout may also be placed in the recessedportions 28 and 30. Shims 74 may be used to level the precast concretebridge elements 14 and 16.

Referring back to FIG. 1, a headwall 76 and wingwalls 78 and 80 areconnected to one or both ends of the arch structure 10. A precast curb82 (represented by dashed lines) may also provided in the precastconcrete bridge elements 14 and 16 that are located at the ends of thestructure to provide support for walls 76, 78 and 80. Referring to FIG.6, the headwall 76 and wingwalls 78 and 80 are connected by a dowel barsplicer system 84.

As shown by FIG. 7, the arch structures 10 can be aligned to formvarious structures, such as bridges. In some embodiments, the archstructures 10 may be configured such that, once aligned, they form acurve portion 86 or a straight portion 88 as required at the particularinstallation.

FIG. 8 shows a schematic side elevation of an arch structure 100 inisolation with rise R, largest span S1, height H to largest span andbottom span S2 shown.

In an alternative embodiment, the upper part of the structure may be ahalf-ellipse shape and the lower legs of the structure may be in theshape of a series of arc segments with ends tangentially connected. Instill another embodiment, the upper part of the structure may be formedby a shape in the form of a series of arc segments with endstangentially connected, and the lower legs of the structure may be inthe shape of a series of arc segments with ends tangentially connected.In either case, the largest span will be defined where the tangent lineof the overall structure is vertical.

A number of detailed embodiments have been described. Nevertheless, itwill be understood that various modifications may be made. For example,multiple units may be connected together end-to-end to form an elongatedbridge/tunnel to be overfilled. Adjacent sections may include jointseals as appropriate. End walls may also be provided for the elongatedbridge/tunnel. Size and location of rebar within the precast elementsmay be varied according to expected overfill height and/or otherrequirements for a given installation. Accordingly, other embodimentsare within the scope of the claims.

1. An overfilled structure, comprising: a footing; first and secondprecast concrete bridge elements that have upper ends connected by acrown joint, the precast concrete bridge elements form an open bottomarch structure that is supported on the footing; the footing extends anentirety of a lower end span of the arch structure and includes spacedapart upwardly facing recesses to receive lower ends of the precastconcrete bridge elements; the precast bridge elements sized and shapedsuch that the arch structure has an upper portion that is formed by afirst half-ellipse shape and a lower portion that is formed by part of asecond half-ellipse shape; the two half-ellipse shapes meet at anelevation along a rise of the arch structure, and such elevation definesa largest span of the arch structure; the arch structure includes lowerends that come back inward toward each other, such that the lower endspan is less than the largest span.
 2. The overfilled structure of claim1 wherein: the largest span is between 18 and 24 feet, the rise isbetween 25 and 30 feet and the lower end span is between 15 and 18 feet;the elevation of the largest span is between 9 and 13 feet from thelower end of the arch structure.
 3. The overfilled structure of claim 1wherein: a ratio of the largest span to the rise is about 75-85%; aratio of the elevation of the largest span to the rise is about 35 to45%.
 4. The overfilled structure of claim 1 wherein the upper end of oneof the precast bridge elements includes a rib that is received in agroove of the upper end of the other precast bridge element.
 5. An archsystem, comprising: at least one footing; at least one precast concretebridge element forming an open bottom arch structure that is supportedon the at least one footing, the arch structure has an upper portion anda lower portion that meet at an elevation along a rise of the archstructure, and such elevation defines a largest span of the archstructure, the arch structure includes lower ends that come back inwardtoward each other, such that a lower end span of the arch structure isless than the largest span.
 6. The arch system of claim 5 wherein: thelargest span is between 18 and 24 feet, the rise is between 25 and 30feet and the lower end span is between 15 and 18 feet; the elevation ofthe largest span is between 9 and 13 feet from the lower end of the archstructure.
 7. The arch system of claim 5 wherein: a ratio of the largestspan to the rise is about 75-85%; a ratio of the height of the largestspan to the rise is about 35 to 45%.
 8. The arch structure of claim 5wherein the footing extends an entirety of the lower end span andincludes spaced apart upwardly facing recesses that receive lower sideends of the arch structure.
 9. The arch structure of claim 8 wherein thefooting include a middle segment that is substantially parallel and endsegments extending upward and outward from the middle segment, eachrecesses located on a respective one of the end segments.
 10. The archstructure of claim 5 wherein the upper portion is formed by a firsthalf-ellipse shape and the lower portion is formed by part of a secondhalf-ellipse shape.
 11. A method of forming an overfilled structure, themethod comprising: precasting first and second concrete bridge elements;moving the precast first and second concrete bridge elements to a site;placing lower ends of the precast first and second concrete bridgeelements in spaced apart, upwardly facing recesses in a footing suchthat the first and second precast bridge elements form an arch structurehaving an open bottom that is spanned by and supported on the footing;joining the precast first and second concrete bridge elements at theirupper ends; the precast first and second concrete bridge elements sizedand shaped such that the arch structure has an upper portion that isformed by a first half-ellipse and a lower portion, the upper and lowerportions meet at an elevation along a rise of the arch structure, andsuch elevation defines a largest span of the arch structure; theresulting arch structure includes the lower ends that come back inwardtoward each other, such that a lower end span of the arch structure isless than the largest span.
 12. The method of claim 11 wherein: thelargest span is between 18 and 24 feet, the rise is between 25 and 30feet and the lower end span is between 15 and 18 feet; wall thickness isbetween 1.1 and 1.5 feet; the elevation of the largest span is between 9and 13 feet from the lower end of the structure.
 13. The method of claim11 wherein: a ratio of the largest span to the rise is about 75-85%; aratio of the height of the largest span to the rise is about 35 to 45%.14. The method of claim 11 wherein the upper end of one of the precastfirst and second bridge elements includes a rib that is received in agroove of the upper end of the other precast first and second bridgeelement.
 15. The method of claim 11 further comprising aligning multiplearch structures forming a tunnel.
 16. The method of claim 11 furthercomprising precasting the footing and locating the footing at the site.17. The method of claim 11 further comprising casting the footing inplace at the site.